1. Field of the Invention
This invention relates to a harness grommet, having a sound-insulating membrane forming a sound-insulating air layer within the grommet, in which the ability of inserting the sound-insulating membrane is enhanced, and also the withdrawal of this membrane is positively prevented.
2. Related Art
In an automobile, a wire harness is arranged between an engine room and a passenger room. The wire harness communicates therebetween through a through hole formed on a body panel located between the engine room and the passenger room. In order to avoid a breakage of the wire harness by contacting the body panel, a grommet is mounted on the through hole.
In the conventional art, a grommet having a configuration as shown in FIG. 7 is used. In FIG. 7, the grommet has a large diameter portion 2 having an engaging recess 2A for engaging the through hole of the body panel and a small diameter portion 4 for fixing the wire harness passing through the large diameter portion 2.
In the engine room, the rain drops enter into the engine room while running. Thus, in order to prevent the rain drops from entering into the passenger room, the grommet 1 is filled up with a liquid molding material 5. For filling the liquid molding material, a cylindrical filling cup 6 is provided at an inner side of the large diameter portion 2.
Further, in order to avoid the transmission of noise from the engine room to the passenger room through the grommet, an air layer 7 is provided at an inner portion of the large diameter portion 2. This air layer 7 is defined by a sound insulating membrane 8 which is integrally formed on the large diameter portion 2 at the other side of the large diameter 2 and is turned back into the small diameter portion 4 and an inner wall surface 2B of the large diameter portion 2.
However, in the conventional grommet, on the assembling line, an operator touches the wire harness and the wire harness 3 is slanted with respect to the body panel to incline the cylindrical filling cup 6. As shown in FIG. 8, a tip portion of the sound insulating membrane is disengaged with the cylindrical filling cup 6 to communicate the air layer 7 with the external portion. Under this condition, the air layer is not effected as considered to omit it, and a sound-insulating characteristic is extremely inferior.
Further, the grommet is formed by the rubber as the elastic material. When the slanted wire harness is to be adjusted to the correct position, the sound-insulating membrane 8 is extended toward a direction opposite to the small diameter portion 4 by the elastic force of the grommet as shown in FIG. 9. As usual, a step of filling the molding material is subjected from a direction A. Thus, if the sound-insulating membrane 8 is opposite to the small diameter portion 4, the mold filling operation becomes very complicated because the sound-insulating membrane becomes an obstacle.